Magnetostatic wave device

ABSTRACT

A magnetostatic wave device includes a Gd 3  Ga 5  O 12  substrate off-angled from a {110} plane. A magnetic thin film including a crystal of garnet is formed on the Gd 3  Ga 5  O 12  substrate by liquid-phase epitaxy. A transducer is operative for exciting magnetostatic wave in the magnetic thin film in response to an RF electric signal. A bias magnetic field is applied to the magnetic thin film. There is a relation as 20°≦|θ 1  +θ 2  |≦35°, where &#34;θ 1  &#34; denotes an angle between a longitudinal direction of the transducer and a &lt;001&gt; orientation of the crystal in the magnetic thin film, and &#34;θ 2  &#34; denotes an angle between a direction of the bias magnetic field and a transverse direction of the transducer which is perpendicular to the longitudinal direction thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a magnetostatic wave device such as amicrowave filter, a resonator, or an S/N (signal-to-noise ratio)enhancer.

2. Description of the Related Art

As an RF signal received by a satellite broadcasting television receiverweakens due to rain, snow (white specks) increases in reproducedpictures on a display of the television receiver. When the received RFsignal falls into an unacceptable range, it is difficult to reproducepictures on the display.

T. Nomoto et al have proposed an S/N enhancer for improving thesignal-to-noise ratio of a received RF television signal (T. Nomoto etal., IEEE Trans. on Microwave Theory and Techniques, Vol. 41, No. 8,August 1993, pp. 1316-1322). This prior-art S/N enhancer is of thecancel type, using two magnetostatic surface wave filters.

Y. Ishikawa et al have developed an adaptor for a satellite broadcastingtelevision receiver (Y. Ishikawa et al., Proc. of 1994 Asia PacificConference, pp. 179-183). This prior-art adaptor uses an S/N enhancerdesigned to operate for a 1.9-GHz band. In the prior-art adaptor, asignal in a first IF band of 1 GHz to 1.3 GHz which is derived from areceived RF signal is up-converted to a 1.9-GHz signal, and the 1.9-GHzsignal is processed by the S/N enhancer. The processing-resultantsignal, that is, the filtering-resultant signal, is down-converted backto a signal in the first IF band. The prior-art adaptor includesfrequency converters in addition to the S/N enhancer. Thus, theprior-art adaptor tends to be expensive.

An S/N enhancer capable of operating at frequencies of 1 GHz to 1.3 GHzhas been desired. Also, an S/N enhancer has been desired which canoperate for a 400-MHz band, that is, a second IF band in a satellitebroadcasting television receiver.

Japanese published unexamined patent application 7-130539 discloses amagnetostatic surface wave device. This prior-art magnetostatic surfacewave device includes a film of single crystal of garnet which is grownon a Gd₃ Ga₅ O₁₂ substrate. The Gd₃ Ga₅ O₁₂ substrate has a planeorientation being one from among (110), (100), and (211). In theprior-art magnetostatic surface wave device, an anisotropic magneticfield can be weak so that the lower limit of the frequency band for thepropagation of magnetostatic surface wave can be a relatively lowfrequency. In Japanese application 7-130539, the lowest frequency ofmagnetostatic surface wave is 900 MHz when a saturation magnetization is1,760 G and the plane orientation of the substrate is (100).Accordingly, it is difficult to use the prior-art magnetostatic surfacewave device as an S/N enhancer operating for a 400-MHz band.

T. Kuki et al have developed a reflection-type S/N enhancer operatingfor a 400-MHz band (T. Kuki et al., 1995 IEEE MTT-S Digest, pp.111-114). To attain an operating frequency of 400 MHz, this prior-artreflection-type S/N enhancer uses a thin film of YIG which has arelatively low saturation magnetization. Since this prior-art S/Nenhance is of the reflection type, the width of an operating frequencyband thereof is a small value equal to 40 MHz. The operating frequencyof this prior-art reflection-type S/N enhancer tends to considerablydepend on an ambient temperature. Accordingly, it is difficult topractically use this prior-art reflection-type S/N enhancer.

T. Kuki et al used a magnetostatic wave in a reflection-type S/Nenhancer designed as a mixture of surface wave and backward volume wave(T. Kuki et al., Manuscript C-106, General Meeting 1996, JapaneseInstitute of Electronics, Information and Communication Engineers). Thisprior-art design is effective in lowering and widening the operatingfrequency band of the reflection-type S/N enhancer although a saturationmagnetization is relatively great. The temperature characteristic of thereflection-type S/N enhancer of the prior-art design has not beeninvestigated. To operate the reflection-type S/N enhancer of theprior-art design, it is necessary to further lower the operatingfrequency thereof.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a magnetostatic wave devicehaving a good temperature characteristic.

It is another object of this invention to provide a magnetostatic wavedevice capable of operating at a further lowered frequency in comparisonwith the prior-art operating frequency.

A first aspect of this invention provides a magnetostatic wave devicecomprising a Gd₃ Ga₅ O₁₂ substrate off-angled from a {110} plane; amagnetic thin film including a crystal of garnet and being formed on theGd₃ Ga₅ O₁₂ substrate by liquid-phase epitaxy; a transducer for excitingmagnetostatic wave in the magnetic thin film in response to an RFelectric signal; and means for applying a bias magnetic field to themagnetic thin film; wherein there is a relation as 20°≦|θ₁ +θ₂ |≦35°,where "θ₁ " denotes an angle between a longitudinal direction of thetransducer and a <001> orientation of the crystal in the magnetic thinfilm, and "θ₂ " denotes an angle between a direction of the biasmagnetic field and a transverse direction of the transducer which isperpendicular to the longitudinal direction thereof.

A second aspect of this invention is based on the first aspect thereof,and provides a magnetostatic wave device wherein the Gd₃ Ga₅ O₁₂substrate is off-angled from the {110} plane by an angle in a range of1° to 5°.

A third aspect of this invention provides a magnetostatic wave devicecomprising a Gd₃ Ga₅ O₁₂ substrate off-angled from a {110} plane; amagnetic thin film including a crystal of garnet and being formed on theGd₃ Ga₅ O₁₂ substrate by liquid-phase epitaxy; a transducer for excitingmagnetostatic wave in the magnetic thin film in response to an RFelectric signal, the transducer including a strip line; and means forapplying a bias magnetic field to the magnetic thin film; wherein thereis a relation as 20°≦|θ₁ +θ₂ |≦35°, where "θ₁ " denotes an angle betweena longitudinal direction of the transducer and a <001> orientation ofthe crystal in the magnetic thin film, and "θ₂ " denotes an anglebetween a direction of the bias magnetic field and a transversedirection of the transducer which is perpendicular to the longitudinaldirection thereof; and wherein there is a relation as |θ₃ |≦75°, where"θ₃ " denotes an angle between a horizontal plane of the magnetic thinfilm and the direction of the bias magnetic field which occurs underconditions where the magnetic thin film and the transducer have beeninclined and rotated about a rotation axis being the strip line of thetransducer.

A fourth aspect of this invention is based on the third aspect thereof,and provides a magnetostatic wave device wherein the Gd₃ Ga₅ O₁₂substrate is off-angled from the {110} plane by an angle in a range of1° to 5°.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram including a perspective view of a functional portionof a magnetostatic wave device according to a first embodiment of thisinvention.

FIG. 2 is a diagram of the relation among the relative level of anoutput power (which corresponds to a reflection loss), the frequency ofthe output power, and an ambient temperature regarding a sample of themagnetostatic wave device in FIG. 1.

FIG. 3 is a diagram of the relation among the relative level of anoutput power (which corresponds to a reflection loss), the frequency ofthe output power, and an ambient temperature regarding a comparativesample.

FIG. 4 is a diagram of various parameters of magnetostatic wave devicesin examples of this invention and comparative examples.

FIG. 5 is a diagram including a perspective view of a functional portionof a magnetostatic wave device according to a second embodiment of thisinvention.

FIG. 6 is la diagram of the relation among a specified angle, atemperature variation range, a center frequency of a reflection loss,and a center frequency variation width regarding a sample of themagnetostatic wave device in FIG. 5.

DESCRIPTION OF THE FIRST PREFERRED EMBODIMENT

With reference to FIG. 1, a magnetostatic wave device (for example, amicrowave filter or a reflection-type S/N enhancer) includes adielectric substrate 1 on which a magnetic thin film 2 of crystal (cubiccrystal) of garnet is formed by, for example, liquid-phase epitaxy. Alower surface or a bottom surface of the dielectric substrate 1 isformed with a ground plane. The magnetic thin film 2 serves as amagnetostatic wave element. The magnetic thin film 2 is off-angled fromor misoriented with respect to the {110} plane of the dielectricsubstrate 1 by a value in the range of 1° to 5°.

In FIG. 1, the numeral 3 denotes the direction of a bias magnetic fieldapplied by a suitable device 9 referred to as a bias magnetic fieldsource.

A transducer 4 provided on the dielectric substrate 1 connects with themagnetic thin film 2. The transducer 4 is used in exciting amagnetostatic wave in response to an RF electric signal (RFelectromagnetic wave). The transducer 4 is designed to provideacceptable impedance matching between an electromagnetic wave andmagnetostatic wave. An input/output port 5 provided on the dielectricsubstrate 1 connects with the transducer 4.

In FIG. 1, the numeral 6 denotes a transverse direction of thetransducer 4 which agrees with a direction of the propagation ofmagnetostatic wave. The transverse direction 6 is in a horizontal plane,and is perpendicular to the longitudinal direction 8 of the transducer4. Here, the horizontal plane is defined as a plane parallel to an uppersurface (a major or main surface) of the magnetic thin film 2 or thedielectric substrate 1. In addition, the numeral 7 denotes the <001>orientation of the crystal in the magnetic thin film 2. Furthermore, thecharacter θ₁ denotes the angle between the longitudinal direction 8 ofthe transducer 4 and the <001> orientation 7 of the magnetic thin film2, and the character θ₂ denotes the angle between the direction 3 of thebias magnetic field and the transverse direction 6 of the transducer 4in a horizontal plane.

Positive values of the angles θ₁ and θ₂ are defined as being alongclockwise directions while negative values of the angles θ₁ and θ₂ aredefined as being along counterclockwise directions.

The mode of the propagation of excited magnetostatic wave in themagnetostatic wave element (the magnetic thin film 2) of themagnetostatic wave device is one among a mode using only magnetostaticsurface wave (MSSW), a mode using only magnetostatic backward volumewave (MSBVW), and a mode using a mixture of magnetostatic surface wave(MSSW) and magnetostatic backward volume wave (MSBVW).

The frequency "f" (MHz) of magnetostatic wave excited in the moderelated to magnetostatic backward volume wave (MSBVW) is approximatelygiven by the following equation.

    f=γ{(H+Ha)·(H+Ha+4πMs)}.sup.1/2          (1)

where "H" denotes the bias magnetic field; "Ha" denotes the anisotropicmagnetic field caused by a 1-order anisotropy constant of the cubiccrystal; "4πMs" denotes the saturation magnetization of the magneticthin film 2; and "γ" denotes a rotational magnetism ratio (2.8 MHz/Oe).

The saturation magnetization "4πMs" of the magnetic thin film 2 and theanisotropic magnetic field Ha depend on an ambient temperature.Accordingly, the frequency "f" of excited magnetostatic wave depends onan ambient temperature in the case where a constant magnetic field isapplied as the bias magnetic field H.

The anisotropic magnetic field Ha varies as a function of the crystalorientation, the saturation magnetization "4πMs", and the 1-orderanisotropy constant K₁. The anisotropic magnetic field Ha is expressedas follows.

    Ha={2-(5/2)·sin.sup.2 θ-(15/8)·sin.sup.2 (2θ)}K.sub.1 /4πMs                               (2)

where "θ" denotes the angle between the <001> orientation and thedirection of the bias magnetic field or an RF magnetic field in the{110} plane of the dielectric substrate 1. According to the equation(2), the anisotropic magnetic field Ha is nullified when the angle "θ"is equal to about ±30°. The sign of the anisotropic magnetic field Ha isinverted when the angle "θ" moves across one of the points equal toabout ±30°. When the bias magnetic field "H" is equal to or weaker thanseveral tens of gauss, temperature dependencies of first and secondparenthesized terms in the square root in the equation (1) can becanceled by each other. Thus, in this case, the frequency "f" of excitedmagnetostatic wave can be constant and independent of a temperaturevariation.

Accordingly, the frequency "f" of excited magnetostatic wave can bestabilized against an ambient temperature variation by optimizing thedirection of the bias magnetic field or the RF magnetic field in thecase where the excited magnetic wave is in the mode being one among themode using only magnetostatic surface wave (MSSW), the mode using onlymagnetostatic backward volume wave (MSBVW), and the mode using a mixtureof magnetostatic surface wave (MSSW) and magnetostatic backward volumewave (MSBVW).

To determine conditions for stabilizing the frequency "f" against anambient temperature variation by optimizing the direction of the biasmagnetic field or the RF magnetic field, the relation between thefrequency "f" and the ambient temperature variation was investigated atdifferent values of the angles θ₁ and θ₂. As previously explained, theangle θ₁ agrees with the angle between the longitudinal direction 8 ofthe transducer 4 and the <001> orientation 7 of the magnetic thin film2, and the angle θ₂ agrees with the angle between the direction 3 of thebias magnetic field and the transverse direction 6 of the transducer 4in a horizontal plane. The transverse direction 6 of the transducer 4 isperpendicular to the longitudinal direction 8 thereof.

It was found from the result of the investigation that the width of thevariation in the center frequency of a reflection loss of themagnetostatic wave device (which corresponds to the width of thevariation in the frequency "f") in response to the ambient temperaturevariation agreed with a remarkably small value or an acceptable valueequal to lower than 15 MHz when the sum of the angles θ₁ and θ₂ was inthe range of 20° to 35°. The garnet crystal in the magnetic thin film 2was cubic, and was hence symmetrical with respect to the <001>orientation 7. Accordingly, it was also found that the width of thevariation in the center frequency of a reflection loss of themagnetostatic wave device in response to the ambient temperaturevariation was remarkably small and was hence acceptable when the sum ofthe angles θ₁ and θ₂ was in the range of -20° to -35°. On the otherhand, the width of the variation in the center frequency of a reflectionloss of the magnetostatic wave device in response to the ambienttemperature variation was unacceptable when the sum of the angles θ₁ andθ₂ was outside the range of 20° to 35° or the range of -20° to -35°.

To attain a good temperature characteristic of the magnetostatic wavedevice, it is preferable that the sum of the angles θ₁ and θ₂ is in therange of 20° to 35° or the range of -20° to -35°.

T. Hibiya has reported that during liquid-phase epitaxy on a {110}garnet substrate, crystal tends to abnormally grow, and that a thickfilm of the crystal is hardly available in this case (T. Hibiya, J.Crystal Growth, 62, p. 87 (1983)). Also, T. Hibiya has reported that useof an off-angled substrate slightly inclined with respect to the {110}plane enables the formation of a thick film.

Experiments were carried out as follows. During the experiments,magnetic thin films of crystal were grown on {110} off-angled ormisoriented substrates by liquid-phase epitaxy. Transducers for excitingmagnetostatic wave were provided on the {110} off-angled substrates.Thereby, various samples of a magnetostatic wave device were fabricated.There were various relations between the crystal orientations and thetransducer orientations. Regarding each of the samples, a measurementwas made as to a variation of the frequency of excited magnetostaticwave in response to an ambient temperature variation under conditionswhere a constant bias magnetic field was applied and the excitedmagnetostatic wave was in one among the mode using only magnetostaticsurface wave (MSSW), the mode using only magnetostatic backward volumewave (MSBVW), and the mode using a mixture of magnetostatic surface wave(MSSW) and magnetostatic backward volume wave (MSBVW). Thus, a variationof the frequency of excited magnetostatic wave in response to an ambienttemperature variation was measured while the relation between thecrystal orientation and the transducer orientation was changed amongvarious types. It was found from the results of the measurements thatthe excitation frequency of magnetostatic wave was substantiallyunchanged in response to an ambient temperature variation in the case ofa specified relation between the crystal orientation and the transducerorientation.

It is preferable that the magnetic thin film 2 of garnet, that is, themagnetostatic wave element, is formed by liquid-phase epitaxy on a Gd₃Ga₅ O₁₂ substrate which is off-angled from or misoriented with respectto the {110} plane by a value in the range of 1° to 5°. When theoff-angle is smaller than 1°, crystal tends to abnormally grow so that athick film of the crystal is hardly available. When the off-angleexceeds 5°, the FMR (ferromagnetic resonance) linewidth ΔH of themagnetic thin film 2 tends to be unacceptably great.

EXAMPLE 1

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated as follows. AGd₃ Ga₅ O₁₂ substrate was prepared which was off-angled from the {110}plane by 3°. A magnetic thin film of YIG crystal having composition"La₀.12 Y₂.88 Fe₄.46 Ga₀.54 O₁₂ " was grown on the Gd₃ Ga₅ O₁₂ substrateby liquid-phase epitaxy. The magnetic thin film had a thickness of 59μm. The magnetic thin film exhibited a saturation magnetization "4πMs"of 920 G at a room temperature. Regarding the magnetic thin film, thehalf-value width (the FMR linewidth) ΔH was equal to 1.3 Oe.

The magnetic thin film was cut and shaped into a rectangular chip in amanner such that the longitudinal direction of the chip was parallel tothe <001> orientation of the crystal. The chip had a size of 12 mm by 8mm. A sample of the magnetostatic wave device was completed which usedthe magnetic thin film chip. The sample of the magnetostatic wave devicehad the structure of FIG. 1.

In the sample of the magnetostatic wave device, the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 25°. The angle θ₂between the direction of the bias magnetic field and the transversedirection of the transducer in a horizontal plane was equal to 0°. Thetransverse direction of the transducer was perpendicular to thelongitudinal direction thereof.

The sample of the magnetostatic wave device causes a reflection losswhen magnetostatic wave was excited in the magnetic thin film. Regardingthe sample of the magnetostatic wave device, measurements were made asto variations in the center frequency of the reflection loss while amagnetic field having a strength of 40 G was applied as a bias magneticfield and an ambient temperature was changed from 0° to 90°. The resultsof the measurements are shown in FIG. 2.

As shown in FIG. 2, the center frequency of the reflection loss providedby the sample of the magnetostatic wave device was equal to 596 MHz at aroom temperature. When the temperature was changed from 0° to 90°, thewidth of the variation in the center frequency of the reflection losswas equal to 12.1 MHz. The width "Δf" of a band, in which an enhancementamount of at least 10 dB was available, was equal to 22 MHz. Theseparameters indicated that the sample of the magnetostatic wave devicehad a good temperature characteristic, and could be used as an effectivemicrowave filter or an effective S/N enhancer.

EXAMPLE 2

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 0°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 20°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 653 MHz at aroom temperature. When the temperature was changed from 30° to 80°, thewidth of the variation in the center frequency of the reflection losswas equal to 3.1 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

EXAMPLE 3

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 0°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 25°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 736 MHz at aroom temperature. When the temperature was changed from 27° to 80°, thewidth of the variation in the center frequency of the reflection losswas equal to 5.1 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

EXAMPLE 4

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 0°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 30°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 790 MHz at aroom temperature. When the temperature was changed from 31° to 80°, thewidth of the variation in the center frequency of the reflection losswas equal to 8.2 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

EXAMPLE 5

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 10°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 15°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 578 MHz at aroom temperature. When the temperature was changed from 30° to 82°, thewidth of the variation in the center frequency of the reflection losswas equal to 1.5 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

EXAMPLE 6

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 15°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 5°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 617 MHz at aroom temperature. When the temperature was changed from 28° to 81°, thewidth of the variation in the center frequency of the reflection losswas equal to 13.3 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

EXAMPLE 7

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 20°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 10°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 513 MHz at aroom temperature. When the temperature was changed from 30° to 80°, thewidth of the variation in the center frequency of the reflection losswas equal to 13.7 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

EXAMPLE 8

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 30°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto -10°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 628 MHz at aroom temperature. When the temperature was changed from 29° to 83°, thewidth of the variation in the center frequency of the reflection losswas equal to 10.7 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

EXAMPLE 9

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 30°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 0°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 641 MHz at aroom temperature. When the temperature was changed from 29° to 97°, thewidth of the variation in the center frequency of the reflection losswas equal to 13.5 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

EXAMPLE 10

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 1 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 30°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 5°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 1. The center frequency of the reflection loss provided bythe sample of the magnetostatic wave device was equal to 643 MHz at aroom temperature. When the temperature was changed from 27° to 81°, thewidth of the variation in the center frequency of the reflection losswas equal to 2.3 MHz. These parameters indicated that the sample of themagnetostatic wave device had a good temperature characteristic.

Comparative Example 1

A comparative sample of the magnetostatic wave device (for example, themicrowave filter or the reflection-type S/N enhancer) was fabricatedwhich was similar to that in Example 1 except that the angle θ₁ betweenthe longitudinal direction of the transducer and the <001> orientationof the crystal in the magnetic thin film was equal to 0°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 0°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the comparative sample of the magnetostatic wave devicewere measured as in Example 1. The results of the measurements are shownin FIG. 3.

As shown in FIG. 3, the center frequency of the reflection loss providedby the comparative sample of the magnetostatic wave device was equal to655 MHz at a room temperature. When the temperature was changed from 23°to 81°, the width of the variation in the center frequency of thereflection loss was equal to 39.6 MHz. Thus, in the comparative sampleof the magnetostatic wave device, the center frequency of the reflectionloss had a considerable temperature dependency.

Comparative Example 2

A comparative sample of the magnetostatic wave device (for example, themicrowave filter or the reflection-type S/N enhancer) was fabricatedwhich was similar to that in Example 1 except that the angle θ₁ betweenthe longitudinal direction of the transducer and the <001> orientationof the crystal in the magnetic thin film was equal to 30°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 10°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the comparative sample of the magnetostatic wave devicewere measured as in Example 1. The center frequency of the reflectionloss provided by the comparative sample of the magnetostatic wave devicewas equal to 554 MHz at a room temperature. When the temperature waschanged from 28° to 80°, the width of the variation in the centerfrequency of the reflection loss was equal to 45.9 MHz. Thus, in thecomparative sample of the magnetostatic wave device, the centerfrequency of the reflection loss had a considerable temperaturedependency.

Conclusion

The measurement result parameters available in Examples 1-10 andComparative Examples 1 and 2 are shown in FIG. 4. It was found from FIG.4 that the width of the variation in the center frequency of thereflection loss in response to the temperature variation was equal to aremarkably small value or an acceptable value less than 15 MHz when thesum of the angles θ₁ and θ₂ was in the range of 20° to 35°. Also, it wasfound that the width of the variation in the center frequency of thereflection loss in response to the temperature variation was acceptablysmall when the sum of the angles θ₁ and θ₂ was in the range of -20° to-35°.

Accordingly, the magnetostatic wave device can effectively operate whenthe sum of the angles θ₁ and θ₂ is in the range of 20° to 35° or therange of -20° to -35°.

DESCRIPTION OF THE SECOND PREFERRED EMBODIMENT

With reference to FIG. 5, a magnetostatic wave device (for example, amicrowave filter or a reflection-type S/N enhancer) includes adielectric substrate 11 on which a magnetic thin film 12 of crystal(cubic crystal) of garnet is formed by, for example, liquid-phaseepitaxy. A lower surface or a bottom surface of the dielectric substrate11 is formed with a ground plane. The magnetic thin film 12 serves as amagnetostatic wave element. The magnetic thin film 12 is off-angled fromor misoriented with respect to the {110} plane of the dielectricsubstrate 11 by a value in the range of 1° to 5°.

In FIG. 5, the numeral 13 denotes the direction of a bias magnetic fieldapplied by a suitable device 10 referred to as a bias magnetic fieldsource.

A transducer 14 provided on the dielectric substrate 11 connects withthe magnetic thin film 12. The transducer 14 is used in excitingmagnetostatic wave in response to an RF electric signal (RFelectromagnetic wave). The transducer 14 is designed to provideacceptable impedance matching between electromagnetic wave andmagnetostatic wave. Generally, the transducer 14 includes a strip lineextending on the dielectric substrate 11. An input/output port 15provided on the dielectric substrate 11 connects with the transducer 14.

In FIG. 5, the numeral 16 denotes a transverse direction of thetransducer 14 which agrees with a direction of the propagation ofmagnetostatic wave. The transverse direction 16 is in a horizontalplane, and is perpendicular to the longitudinal direction 18 of thetransducer 14. Here, the horizontal plane is defined as a plane parallelto an upper surface (a main or major surface) of the magnetic thin film12 or the dielectric substrate 11. In addition, the numeral 17 denotesthe <001> orientation of the crystal in the magnetic thin film 12.Furthermore, the character θ₁ denotes the angle between the longitudinaldirection 18 of the transducer 14 and the <001> orientation 17 of themagnetic thin film 12, and the character θ₂ denotes the angle betweenthe direction 13 of the bias magnetic field and the transverse direction16 of the transducer 14 in a horizontal plane.

Positive values of the angles θ₁ and θ₂ are defined as being alongclockwise directions while negative values of the angles θ₁ and θ₂ aredefined as being along counterclockwise directions.

In FIG. 5, the character θ₃ denotes the angle between a horizontal planeof the magnetic thin film 12 and the direction 13 of the bias magneticfield which occurs when the magnetic thin film 12 and the transducer 14have been inclined and rotated about a rotation axis being the stripline of the transducer 14. Here, the upper surface (the main or majorsurface) of the magnetic thin film 12 is defined as the horizontal planethereof.

A positive value of the angle θ₃ is defined as being along a clockwisedirection while a negative value of the angle θ₃ is defined as beingalong a counterclockwise direction.

To attain a good temperature characteristic and a further loweredoperating frequency of the magnetostatic wave device, it is preferablethat the absolute value of the sum of the angles θ₁ and θ₂ is in therange of 20° to 35°, and that the absolute value of the angle θ₃ isequal to or smaller than 75°. In other words, it is preferable that20°≦|θ₁ +θ₂ |≦35°, and |θ₃ |≦75°. When the angles θ₁, θ₂, and θ₃ areoutside the above-indicated ranges, it tends to be difficult to providea good temperature characteristic and a further lowered operatingfrequency of the magnetostatic wave device.

The mode of the propagation of excited magnetostatic wave in themagnetostatic wave element (the magnetic thin film 12) of themagnetostatic wave device is one among a mode using only magnetostaticsurface wave (MSSW), a mode using only magnetostatic backward volumewave (MSBVW), and a mode using a mixture of magnetostatic surface wave(MSSW) and magnetostatic backward volume wave (MSBVW).

The frequency "f" (MHz) of magnetostatic wave excited in the moderelated to magnetostatic backward volume wave (MSBVW) is approximatelygiven by the previously-indicated equation (1). The saturationmagnetization "4πMs" of the magnetic thin film 12 and the anisotropicmagnetic field Ha depend on an ambient temperature. Accordingly, thefrequency "f" of excited magnetostatic wave depends on the ambienttemperature in the case where a constant magnetic field is applied asthe bias magnetic field H.

The anisotropic magnetic field Ha varies as a function of the crystalorientation, the saturation magnetization "4πMs" , and the 1-orderanisotropy constant K₁. The anisotropic magnetic field Ha is expressedby the previously-indicated equation (2). As previously explained, thecharacter "θ" in the equation (2) denotes the angle between the <001>orientation and the direction of the bias magnetic field or an RFmagnetic field in the {110} plane of the dielectric substrate 11.According to the equation (2), the anisotropic magnetic field Ha isnullified when the angle "θ" is equal to about ±30°. The sign of theanisotropic magnetic field Ha is inverted when the angle "θ" movesacross one of the points equal to about ±30°. When the bias magneticfield "H" is equal to or weaker than several tens of gauss, temperaturedependencies of first and second parenthesized terms in the square rootin the equation (1) can be canceled by each other. Thus, in this case,the frequency "f" of excited magnetostatic wave can be constant andindependent of a temperature variation.

Accordingly, the frequency "f" of excited magnetostatic wave can bestabilized against an ambient temperature variation by optimizing thedirection of the bias magnetic field or the RF magnetic field in thecase where the excited magnetic wave is in the mode being one among themode using only magnetostatic surface wave (MSSW), the mode using onlymagnetostatic backward volume wave (MSBVW), and the mode using a mixtureof magnetostatic surface wave (MSSW) and magnetostatic backward volumewave (MSBVW).

To determine conditions for stabilizing the frequency "f" against anambient temperature variation by optimizing the direction of the biasmagnetic field or the RF magnetic field, the relation between thefrequency "f" and the ambient temperature variation was investigated atdifferent values of the angles θ₁, θ₂, and θ₃. As previously explained,the angle θ₁ agrees with the angle between the longitudinal direction 18of the transducer 14 and the <001> orientation 17 of the magnetic thinfilm 12, and the angle θ₂ agrees with the angle between the direction 13of the bias magnetic field and the transverse direction 16 of thetransducer 14 in a horizontal plane. The transverse direction 16 of thetransducer 14 is perpendicular to the longitudinal direction 18 thereof.In addition, the angle θ₃ agrees with the angle between the horizontalplane of the magnetic thin film 12 and the direction 13 of the biasmagnetic field which occurs when the magnetic thin film 12 and thetransducer 14 have been inclined and rotated about a rotation axis beingthe strip line of the transducer 14.

It was found from the result of the investigation that the width of thevariation in the center frequency of a reflection loss of themagnetostatic wave device (which corresponds to the width of thevariation in the frequency "f") in response to the ambient temperaturevariation agreed with a remarkably small value or an acceptable valueequal to less than 15 MHz when the sum of the angles θ₁ and θ₂ was inthe range of 20° to 35°. The garnet crystal in the magnetic thin film 12was cubic, and was hence symmetrical with respect to the <001>orientation 17. Accordingly, it was also found that the width of thevariation in the center frequency of a reflection loss of themagnetostatic wave device in response to the ambient temperaturevariation was acceptably small when the sum of the angles θ₁ and θ₂ wasin the range of -20° to -35°. On the other hand, the width of thevariation in the center frequency of a reflection loss of themagnetostatic wave device in response to the ambient temperaturevariation was unacceptable when the sum of the angles θ₁ and θ₂ wasoutside the range of 20° to 35° or the range of -20° to -35°. Also, itwas found from the result of the investigation that the excitation ofmagnetostatic wave succeeded when the absolute value of the angle θ₃ wasequal to or smaller than 75°. On the other hand, magnetostatic wave wasnot sufficiently excited when the absolute value of the angle θ₃ wasgreater than 75°.

To attain a good temperature characteristic and a further loweredoperating frequency of the magnetostatic wave device, it is preferablethat the sum of the angles θ₁ and θ₂ is in the range of 20° to 35° orthe range of -20° to -35°, and that the absolute value of the angle θ₃is equal to or smaller than 75°.

T. Hibiya has reported that during liquid-phase epitaxy on a {110}garnet substrate, crystal tends to abnormally grow, and that a thickfilm of the crystal is hardly available in this case (T. Hibiya, J.Crystal Growth, 62, p. 87 (1983)). Also, T. Hibiya has reported that useof an off-angled substrate slightly inclined with respect to the {110}plane enables the formation of a thick film.

Experiments were carried out as follows. During the experiments,magnetic thin films of crystal were grown on {110} off-angled ormisoriented substrates by liquid-phase epitaxy. Transducers for excitingmagnetostatic wave were provided on the {110} off-angled substrates.Thereby, various samples of a magnetostatic wave device were fabricated.There were various relations between the crystal orientations and thetransducer orientations. Regarding each of the samples, a measurementwas made as to a variation of the frequency of excited magnetostaticwave in response to an ambient temperature variation under conditionswhere a constant bias magnetic field was applied and the direction ofthe applied magnetic field was changed, and the excited magnetostaticwave was in one among the mode using only magnetostatic surface wave(MSSSW), the mode using only magnetostatic backward volume wave (MSBVW),and the mode using a mixture of magnetostatic surface wave (MSSW) andmagnetostatic backward volume wave (MSBVW). Thus, a variation of thefrequency of excited magnetostatic wave in response to an ambienttemperature variation was measured while the relation between thecrystal orientation and the transducer orientation was changed amongvarious types and also the direction of the applied magnetic field waschanged among various values. It was found from the results of themeasurements that the excitation frequency of magnetostatic wave wassubstantially unchanged in response to an ambient temperature variationin the case of specified conditions of the crystal orientation, thetransducer orientation, and the applied magnetic field direction.

It is preferable that the magnetic thin film 12 of garnet, that is, themagnetostatic wave element, is formed by liquid-phase epitaxy on a Gd₃Ga₅ O₁₂ substrate which is off-angled from or misoriented with respectto the {110} plane by a value in the range of 1° to 5°. When theoff-angle is smaller than 1°, crystal tends to abnormally grow so that athick film of the crystal is hardly available. When the off-angleexceeds 5°, the FMR (ferromagnetic resonance) linewidth ΔH of themagnetic thin film 12 tends to be unacceptably great.

EXAMPLE 11

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated as follows. AGd₃ Ga₅ O₁₂ substrate was prepared which was off-angled from the {110}plane by 3°. A magnetic thin film of YIG crystal having composition"La₀.12 Y₂.88 Fe₄.46 Ga₀.54 O₁₂ " was grown on the Gd₃ Ga₅ O₁₂ substrateby liquid-phase epitaxy. The magnetic thin film had a thickness of 59μm. The magnetic thin film exhibited a saturation magnetization "4πMs"of 920 G at a room temperature. Regarding the magnetic thin film, thehalf-value width (the FMR linewidth) ΔH was equal to 1.3 Oe.

The magnetic thin film was cut and shaped into a rectangular or squarechip in a manner such that a pair of opposite side surfaces of the chipextended in directions parallel to the <001> orientation. The chip had asize of, for example, 12 mm by 12 mm. A sample of the magnetostatic wavedevice was completed which used the magnetic thin film chip. The sampleof the magnetostatic wave device had the structure of FIG. 5.

In the sample of the magnetostatic wave device, the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 20°. The angle θ₂between the direction of the bias magnetic field and the transversedirection of the transducer in a horizontal plane was equal to 0°. Thetransverse direction of the transducer is perpendicular to thelongitudinal direction thereof. As previously explained, the angle θ₃agrees with the angle between the horizontal plane of the magnetic thinfilm and the direction of the bias magnetic field which occurs when themagnetic thin film and the transducer have been inclined and rotatedabout a rotation axis being the strip line of the transducer.

The sample of the magnetostatic wave device causes a reflection losswhen magnetostatic wave was excited in the magnetic thin film. Regardingthe sample of the magnetostatic wave device, measurements were made asto the center frequency of the reflection loss and variations in thecenter frequency while a magnetic field having a constant strength wasapplied as a bias magnetic field and an ambient temperature was changedfrom a room temperature level to about 80°, and also the angle θ₃ waschanged among various values. During the measurements, the temperaturechange and the applied magnetic field were adjusted so that the width ofeach center frequency variation was limited to 15 MHz or smaller. Theresults of the measurements are shown in FIG. 6.

With reference to FIG. 6, the center frequency of the reflection losswhich related to a good temperature characteristic dropped as the angleθ₃ was changed from 0° in a clockwise direction or a counterclockwisedirection. The center frequency of the reflection loss was minimizedwhen the angle θ₃ reached about ±65°. Specifically, the center frequencyof the reflection loss was equal to 455 MHz when the angle θ₃ was equalto -65°. On the other hand, the center frequency of the reflection losswas equal to 604 MHz when the angle θ₃ was equal to 0°. Thus, the centerfrequency of the reflection loss at an angle θ₃ of -65° was lower thanthat at an angle θ₃ of 0° by about 50 MHz. The center frequency of thereflection loss rose as the angle θ₃ was changed from about ±65° toward+90° or -90° in the clockwise direction or the counterclockwisedirection. The center frequency of the reflection loss at an angle θ₃ of±75° was comparable to that at an angle θ₃ of 0°. Magnetostatic wave wasnot excited when the absolute value of the angle θ₃ was equal to orgreater than 82°.

EXAMPLE 12

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 11 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 20°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 10°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 11. According to the measurement results, the centerfrequency of the reflection loss which related to a good temperaturecharacteristic dropped as the angle θ₃ was changed from 0° in aclockwise direction or a counterclockwise direction. The centerfrequency of the reflection loss was minimized when the angle θ₃ reachedabout ±65°. Specifically, the center frequency of the reflection losswas equal to 432 MHz when the angle θ₃ was equal to -65°. The centerfrequency of the reflection loss at an angle θ₃ of -65° was lower thanthat at an angle θ₃ of 0° by about 80 MHz. The center frequency of thereflection loss rose as the angle θ₃ was changed from about ±65° toward+90° or -90° in the clockwise direction or the counterclockwisedirection. The center frequency of the reflection loss at an angle θ₃ of±75° was comparable to that at an angle θ₃ of 0°. Magnetostatic wave wasnot excited when the absolute value of the angle θ₃ was equal to orgreater than 82°.

EXAMPLE 13

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 11 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 0°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 20°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 11. According to the measurement results, the centerfrequency of the reflection loss which related to a good temperaturecharacteristic dropped as the angle θ₃ was changed from 0° in aclockwise direction or a counterclockwise direction. The centerfrequency of the reflection loss was minimized when the angle θ₃ reachedabout ±65°. The center frequency of the reflection loss at an angle θ₃of -65° was lower than that at an angle θ₃ of 0° by about 52 MHz. Thecenter frequency of the reflection loss rose as the angle θ₃ was changedfrom about ±65° toward +90° or -90° in the clockwise direction or thecounterclockwise direction. The center frequency of the reflection lossat an angle θ₃ of ±75° was comparable to that at an angle θ₃ of 0°.Magnetostatic wave was not excited when the absolute value of the angleθ₃ was equal to or greater than 82°.

EXAMPLE 14

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 11 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 15°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 10°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 11. According to the measurement results, the centerfrequency of the reflection loss which related to a good temperaturecharacteristic dropped as the angle θ₃ was changed from 0° in aclockwise direction or a counterclockwise direction. The centerfrequency of the reflection loss was minimized when the angle θ₃ reachedabout ±65°. The center frequency of the reflection loss at an angle θ₃of -65° was lower than that at an angle θ₃ of 0° by about 51 MHz. Thecenter frequency of the reflection loss rose as the angle θ₃ was changedfrom about ±65° toward +90° or -90° in the clockwise direction or thecounterclockwise direction. The center frequency of the reflection lossat an angle θ₃ of ±75° was comparable to that at an angle θ₃ of 0°.Magnetostatic wave was not excited when the absolute value of the angleθ₃ was equal to or greater than 82°.

EXAMPLE 15

A sample of the magnetostatic wave device (for example, the microwavefilter or the reflection-type S/N enhancer) was fabricated which wassimilar to that in Example 11 except that the angle θ₁ between thelongitudinal direction of the transducer and the <001> orientation ofthe crystal in the magnetic thin film was equal to 30°, and that theangle θ₂ between the direction of the bias magnetic field and thetransverse direction of the transducer in a horizontal plane was equalto 5°. The transverse direction of the transducer was perpendicular tothe longitudinal direction thereof.

Parameters of the sample of the magnetostatic wave device were measuredas in Example 11. According to the measurement results, the centerfrequency of the reflection loss which related to a good temperaturecharacteristic dropped as the angle θ₃ was changed from 0° in aclockwise direction or a counterclockwise direction. The centerfrequency of the reflection loss was minimized when the angle θ₃ reachedabout ±65°. The center frequency of the reflection loss at an angle θ₃of -65° was lower than that at an angle θ₃ of 0° by about 101 MHz. Thecenter frequency of the reflection loss rose as the angle θ₃ was changedfrom about ±65° toward +90° or -90° in the clockwise direction or thecounterclockwise direction. The center frequency of the reflection lossat an angle θ₃ of ±75° was comparable to that at an angle θ₃ of 0°.Magnetostatic wave was not excited when the absolute value of the angleθ₃ was equal to or greater than 82°.

Conclusion

It was found from the measurement results regarding Examples 11-15 thatthe center frequency of the reflection loss provided by themagnetostatic wave device was relatively low when the angle θ₃ was inthe range of 0° to about +75° or the range of 0° to about -75°. Also, itwas found that the center frequency of the reflection loss at an angleθ₃ of -65° was lower than that at an angle θ₃ of 0° by greater than 50MHz. Thus, it is preferable that the angle θ₃ is in the range of 0° toabout +75° or the range of 0° to about -75°. It is more preferable thatthe angle θ₃ is in the range of 20° to about +65° or the range of -20°to about -65°.

What is claimed is:
 1. A magnetostatic wave device comprising:a Gd₃ Ga₅O₁₂ substrate off-angled from a {110} plane; a magnetic thin filmincluding a crystal of garnet and being formed on the Gd₃ Ga₅ O₁₂substrate by liquid-phase epitaxy; a transducer for excitingmagnetostatic wave in the magnetic thin film in response to an RFelectric signal; and means for applying a bias magnetic field to themagnetic thin film; wherein there is a relation as 20°≦|θ₁ +θ₂ |≦35°,where "θ₁ " denotes an angle between a longitudinal direction of thetransducer and a <001> orientation of the crystal in the magnetic thinfilm, and "θ₂ " denotes an angle between a direction of the biasmagnetic field and a transverse direction of the transducer which isperpendicular to the longitudinal direction thereof.
 2. A magnetostaticwave device as recited in claim 1, wherein the Gd₃ Ga₅ O₁₂ substrate isoff-angled from the {110} plane by an angle in a range of 1° to 5°.
 3. Amagnetostatic wave device comprising:a Gd₃ Ga₅ O₁₂ substrate off-angledfrom a {110} plane; a magnetic thin film including a crystal of garnetand being formed on the Gd₃ Ga₅ O₁₂ substrate by liquid-phase epitaxy; atransducer for exciting magnetostatic wave in the magnetic thin film inresponse to an RF electric signal, the transducer including a stripline; and means for applying a bias magnetic field to the magnetic thinfilm; wherein there is a relation as 20°≦|θ₁ +θ₂ |≦35°, where "θ₁ "denotes an angle between a longitudinal direction of the transducer anda <001> orientation of the crystal in the magnetic thin film, and "θ₂ "denotes an angle between a direction of the bias magnetic field and atransverse direction of the transducer which is perpendicular to thelongitudinal direction thereof; and wherein there is a relation as |θ₃|≦75°, where "θ₃ " denotes an angle between a horizontal plane of themagnetic thin film and the direction of the bias magnetic field whichoccurs under conditions where the magnetic thin film and the transducerhave been inclined and rotated about a rotation axis being the stripline of the transducer.
 4. A magnetostatic wave device as recited inclaim 3, wherein the Gd₃ Ga₅ O₁₂ substrate is off-angled from the {110}plane by an angle in a range of 1° to 5°.